*melanin: the pigment produced by your skin that gives it a tanned colour. 2. Take your time, and build your tan up slowly. Everyone reacts differently to the sun, but here are some guidelines to get you started: If tanning in the sun, start with only 15-20 minutes in the sun on your first session. In your following tanning sessions only increase your time by 5-10 minute increments, and monitor your skin regularly to make sure you arenât starting to go red and burn. If tanning on a sunbed, start with 2-3 minutes.
Over 2,000 years, many imperial dynasties and kingdoms built, rebuilt, and extended walls many times that subsequently eroded. The latest imperial construction was performed by the Ming Dynasty (1368â1644), and the length was then over 6,000 kilometers (3,700 miles). This is the wall often referred to when we talk about the Great Wall.
Great Wall of China. It's hard to say how long because the Great Wall was not built in one go. In the very old time, about 900 BC, many states in China started build some long walls to defend its territory from enemies (neighbouring enemy states, or even northern nomads) . Some of these long wall could be hundreds of kilometres long.